METHODS: Retrospective analysis of ulcerative colitis (UC) and Crohn's disease (CD), diagnosed from January 1980 till June 2018 was conducted at our centre.

RESULTS: A total of 413 IBD patients (281 UC, 132 CD) were identified. Mean crude incidence of IBD has increased steadily over the first three decades: 0.36 (1980-1989), 0.48 (1990-1999) and 0.63 per 100,000 person-years (2000-2009). In the 2010 to 2018 period, the mean crude incidence has doubled to 1.46 per 100,000 person-years. There was a significant rise in the incidence of CD, as depicted by reducing UC:CD ratio: 5:1 (1980-1989), 5:1 (1990-1999), 1.9:1 (2000-2009) and 1.7:1 (2010-2018). The prevalence rate of IBD, UC and CD, respectively were 23.0, 15.67 and 7.36 per 100,000 persons. Of all IBD patients, 61.5% (n = 254) were males. When stratified according to ethnic group, the highest prevalence of IBD was among the Indians: 73.4 per 100,000 persons, followed by Malays: 24.8 per 100,000 persons and Chinese: 14.6 per 100,000 persons. The mean age of diagnosis was 41.2 years for UC and 27.4 years for CD. Majority were non-smokers (UC: 76.9%, CD: 70.5%). The diseases were classified as follows: UC; proctitis (9.2%), left-sided colitis (50.2%) and extensive colitis (40.6%), CD; isolated ileal (22.7%), colonic (28.8%), ileocolonic (47.7%) and upper gastrointestinal (0.8%). 12.9% of CD patients had concurrent perianal disease. Extra intestinal manifestations were observed more in CD (53.8%) as compared to UC (12%). Dysplasia and malignancy, on the other hand, occurred more in UC (4.3%, n = 12) than in CD (0.8%, n = 1). Over one quarter (27.3%) of CD patients and 3.6% of UC patients received biologic therapy.